# curs_util 3x

    curs_util(3x)                                             curs_util(3x)

## NAME

           delay_output, filter, flushinp, getwin, key_name, keyname,
           nofilter, putwin, unctrl, use_env, wunctrl - miscellaneous
           curses utility routines

## SYNOPSIS

           #include <curses.h>

           char *unctrl(chtype c);
           wchar_t *wunctrl(cchar_t *c);
           char *keyname(int c);
           char *key_name(wchar_t w);
           void filter(void);
           void nofilter(void);
           void use_env(bool f);
           int putwin(WINDOW *win, FILE *filep);
           WINDOW *getwin(FILE *filep);
           int delay_output(int ms);
           int flushinp(void);

## DESCRIPTION

           The  unctrl  routine returns a character string which is a
           printable representation of the character c, ignoring  at-
           tributes.   Control characters are displayed in the ^X no-
           tation.  Printing characters are  displayed  as  is.   The
           corresponding  wunctrl  returns a printable representation
           of a wide-character.

           The keyname routine returns a character string correspond-
           ing to the key c:

              -  Printable  characters  are  displayed as themselves,
                 e.g., a one-character string containing the key.

              -  Control characters are displayed in the ^X notation.

              -  DEL (character 127) is displayed as ^?.

              -  Values  above 128 are either meta characters (if the
                 screen has not been initialized, or if meta has been
                 called  with a TRUE parameter), shown in the M-X no-
                 tation, or are displayed as themselves.  In the lat-
                 ter case, the values may not be printable; this fol-
                 lows the X/Open specification.

              -  Values above 256 may be the names of  the  names  of
                 function keys.

              -  Otherwise  (if  there  is no corresponding name) the
                 function returns null, to denote an  error.   X/Open
                 also lists an "UNKNOWN KEY" return value, which some
                 implementations return rather than null.

           The corresponding key_name returns a character string cor-
           responding  to  the wide-character value w.  The two func-
           tions do not return the same set of  strings;  the  latter
           returns null where the former would display a meta charac-
           ter.

           The filter routine, if used, must be called before initscr
           or  newterm  are called.  The effect is that, during those
           calls, LINES is set to 1;  the  capabilities  clear,  cup,
           cud,  cud1,  cuu1,  cuu,  vpa  are  disabled; and the home
           string is set to the value of cr.

           The nofilter routine cancels the  effect  of  a  preceding
           filter  call.   That  allows  the  caller  to initialize a
           screen on a different device, using a different  value  of
           $TERM.   The  limitation arises because the filter routine
           modifies the in-memory copy of the terminal information.

           The use_env routine, if used, is called before initscr  or
           newterm  are  called.   When called with FALSE as an argu-
           ment, the values of lines and  columns  specified  in  the
           terminfo  database will be used, even if environment vari-
           ables LINES and COLUMNS (used by default) are set,  or  if
           curses  is  running in a window (in which case default be-
           havior would be to  use  the  window  size  if  LINES  and
           COLUMNS  are not set).  Note that setting LINES or COLUMNS
           overrides the corresponding size  which  may  be  obtained
           from the operating system.

           The  putwin routine writes all data associated with window
           win into the file to which filep points.  This information
           can be later retrieved using the getwin function.

           The getwin routine reads window related data stored in the
           file by putwin.  The routine then creates and  initializes
           a new window using that data.  It returns a pointer to the
           new window.

           The delay_output routine inserts an ms  millisecond  pause
           in  output.   This  routine should not be used extensively
           because padding characters are  used  rather  than  a  CPU
           pause.   If  no  padding character is specified, this uses
           napms to perform the delay.

           The flushinp routine throws away any  typeahead  that  has
           been  typed  by  the user and has not yet been read by the
           program.

## RETURN VALUE

           Except for flushinp, routines that return an  integer  re-
           turn  ERR upon failure and OK (SVr4 specifies only "an in-
           teger value other than ERR") upon successful completion.

           Routines that return pointers return NULL on error.

           X/Open does not define any error conditions.  In this  im-
           plementation

                  flushinp
                       returns  an error if the terminal was not ini-
                       tialized.

                  putwin
                       returns an  error  if  the  associated  fwrite
                       calls return an error.

## PORTABILITY

           The  XSI  Curses  standard,  Issue 4 describes these func-
           tions.  It states that unctrl and wunctrl  will  return  a
           null  pointer if unsuccessful, but does not define any er-
           ror conditions.  This implementation checks for three cas-
           es:

                  -    the  parameter is a 7-bit US-ASCII code.  This
                       is the case that X/Open Curses documented.

                  -    the parameter is in the range 128-159, i.e., a
                       C1  control  code.   If  use_legacy_coding has
                       been called with a 2 parameter, unctrl returns
                       the  parameter,  i.e.,  a one-character string
                       with the parameter  as  the  first  character.
                       Otherwise,  it  returns  ``~@'', ``~A'', etc.,
                       analogous to ``^@'', ``^A'', C0 controls.

                       X/Open Curses does not document whether unctrl
                       can  be  called  before  initializing  curses.
                       This implementation permits that, and  returns
                       the ``~@'', etc., values in that case.

                  -    parameter  values  outside the 0 to 255 range.
                       unctrl returns a null pointer.

           The SVr4 documentation describes the action of filter only
           in  the  vaguest  terms.   The description here is adapted
           from the XSI Curses standard (which erroneously  fails  to
           describe the disabling of cuu).

           The  strings returned by unctrl in this implementation are
           determined at compile time, showing C1 controls  from  the
           upper-128  codes with a `~' prefix rather than `^'.  Other
           implementations have different conventions.  For  example,
           they  may  show  both sets of control characters with `^',
           and strip the parameter to 7 bits.  Or they may ignore  C1
           controls  and  treat  all of the upper-128 codes as print-
           able.  This implementation uses 8 bits but does not modify
           the string to reflect locale.  The use_legacy_coding func-
           tion allows the caller to change the output of unctrl.

           Likewise, the meta function allows the  caller  to  change
           the  output of keyname, i.e., it determines whether to use
           the `M-' prefix for ``meta'' keys (codes in the range  128
           to 255).  Both use_legacy_coding and meta succeed only af-
           ter curses is initialized.  X/Open Curses does  not  docu-
           ment  the  treatment  of  codes 128 to 159.  When treating
           them as ``meta'' keys (or if keyname is called before ini-
           tializing  curses),  this  implementation  returns strings
           ``M-^@'', ``M-^A'', etc.

           The keyname function may return the names of  user-defined
           string  capabilities which are defined in the terminfo en-
           try via the -x option of tic.  This  implementation  auto-
           matically  assigns  at  run-time  keycodes to user-defined
           strings which begin  with  "k".   The  keycodes  start  at
           KEY_MAX,  but  are not guaranteed to be the same value for
           different runs because user-defined codes are merged  from
           all  terminal  descriptions  which  have been loaded.  The
           use_extended_names function controls whether this data  is
           loaded  when  the  terminal description is read by the li-
           brary.

           The nofilter routine is specific to ncurses.  It  was  not
           supported  on  Version 7, BSD or System V implementations.
           It is recommended that any code depending on  ncurses  ex-
           tensions be conditioned using NCURSES_VERSION.

## SEE ALSO

           legacy_coding(3x), curses(3x), curs_initscr(3x), curs_ker-
           nel(3x), curs_scr_dump(3x), legacy_coding(3x).

                                                              curs_util(3x)